Notice that the TVADPTA exhibits some degree of asymmetry (Asymmetry refers to the fact that there is a mismatch between errors of type \(\mathrm {Z}\)  and errors of type \(\mathrm {X}\)  and \(\mathrm {Y}\) . Asymmetry is quantified by the so-called asymmetry parameter \(\alpha = p_\mathrm {z}/p_\mathrm {x}\)  [1]}, [2]}, [3]}).
